Here are two more books from the Horse Riding & Management Series developed by 5m Publishing. Great resources for horse owners.
Horse Behaviour by Barbara Schoning (a German specialized veterinarian) covers how the horse's brain works, the difference between instinct and learned behavior, how a foal's is developed as well as the mentality of a herd.
Natural Medicine for Horses by Cornelia Wittek (a natural remedy practitioner) explains how common herbs, flowers and fungi can be used to benefit a horse's health. Each item - in alphabetical order - describes the origin, the medicinal properties and how to use them. Such as, Oregano can be used in a warm poultice to soothe over-exertion.
The series can be found on Amazon.com